Overclocking greatly varies due to what hardware is being used and who is doing the overclocking. Always remember that no two pieces of hardware will perform the same, so our results will differ from what you might be able to get.
With stock BIOS settings, the Athlon II X2 250 processor runs with a 200MHz bus speed and an x15.0 multiplier that is used to reach the final core clock of 3.0GHz.
Since the AMD Athlon II X2 250 is multiplier locked the only thing that can be down to overclock the processor is to raise the bus speed (base clock) till the processor becomes unstable. By raising the CPU Core Voltage to 1.46V and increasing the bus speed to 264MHz from 200MHz, we were able to reach an impressive 3.96GHz. Not bad for a system that was running XIGMATEK HDT-S1283 heat sink (air cooling). This is an overclock of 961MHz, which is impressive for an $87 processor.
Moving on to the AMD Phenom II X2 550 we found that with the stock BIOS settings, the processor runs with a
200MHz bus speed and an x15.5 multiplier that is used to reach the
final core clock of 3.1GHz. This processor is multiplier unlocked, so when overclocking you can raise both the multiplier and the bus speed to help ‘fine tune’ the overclock.
We increased the multiplier from x15.5 all the way up to x19 and then increased the bus speed from 200MHz to 215MHz with little effort. This was enough to break the 4GHz mark as the overall clock frequency was 4.09Ghz, which is great. This is an overclock of 985MHz, which is roughly what we saw on the Athlon II X2 250 processor. It seems both of these processors love to be overclocked at we were able to get nearly 1GHz overclocks with air cooling! Not bad for $87 and $102 processors if you ask us.